Article for use in the treatment of leafy vegetables



named-n... 22, 1943 UNITED STATES PATENT-OFFICE" ARTICLE FOB use. IN THETREATMENT or? LEAF! VEGETABLES I. William H. Wilson, Santa Monica,Calif.','-as'signor to Fruit 82 Vegetable Processing 00., Santa Monica,Calil'., a corporation of California No Drawing. Application September16, an;

Serial No.357,028

4 Claims. (Cl. 99-193),

the darkening of the butts of such vegetables during shipment. A largeproportion of the leafy vegetables are shipped long distances to pointsof consumption. During such shipment portions of such vegetables,particularly the stem or butts, have a tendency to discolor and developa reddish cast.

As a result, the purchaser immediately becomes cognizant of the factthat the vegetable is not fresh and very often the consumer must removea section of the stem or butt and perhaps some of the outer leaves inorder to remove the portions which have been discolored. Thisdiscoloration is apparently due to certain oxydases present in thevegetables, which oxydases exude through the stem or butt and throughbruised areas on the ribs. Copending applications filed by me havedisclosed methods of treating the cut stems or butts of leafy vegetablesfor the purpose of inhibiting the discoloration during storage andshipment. The present invention is directed toward certain modificationsof the process.

In my co-pending application Serial No.

322,209 (which has matured into Patent No. 2,215,446) I have describedand claimed a method of inhibiting the discoloration of butts of leafyvegetables by applying thereto. an absorbent material containing certainreducing agents. The present invention is directed toward means wherebythe same end result may be attained by different means,

When leafy vegetables, such as romaine or lettuce, are shipped from thepacking houses to the urban centers of consumption, it is customary tocrate the vegetables and to place layers of crushed ice between layersof the vegetables in the crates. It has been found that in the event thebutts are sprayed with an aqueous solution of one of the reducing agentsparticularly' adapted for this purpose and such sprayed butts are thencovered with crushed ice, the inhibition periodis relatively short. Itis believed that during shipment the crushed ice melts slowly andremoves and washes away whatever small amount of reducing agent solutionmay be left upon the butt as a result of the spraylng, dipping orswabbing operation.

I have found that it is not always necessary to spray the butts :with.one of the reducing agents previouslyfmentioned and that instead. goodresults can-be obtained by placing a sheet of fibrousfmaterialoverthefupturned butts of lettuce in a crate,said-sheetcontaining an alkalior alkali metal salt of ,-an acid from the group ofhyposulfurousfsulfurous, pyrosulfurous and thiosulfuric'acids Thesecompounds may be in corporated i'n' heip aper during manufacturethereof: Either H 'mediately prior to or shortly after thejsheetjoifpaper is applied to the butts, the paperis moistened withwater. Instead of moistening. the; paper with water, suitable moisturemay-bederived from the crushed ice which is ordinarily 'placed betweenlayers of lettuce in a crate, the melting i'ce, being absorbed by thepaper during shipment.

An object of the present invention is to disclose and provide, 1 asv anarticle of commerce, an absorbent material in sheet form, said materialcontaining ingredients and compounds capable of inhibiting. thedarkening of butts when saidsheet-material is placed thereover.

This and other objects of the invention will become apparent to thoseskilled in the art from the following description thereof.

A material suitable for use in the process of this invention comprisesan absorbent paper somewhat similar in texture, pliability and porosityto blotting paper. Suitable absorbent sheet material should weigh notvless than about pounds per ream and papers weighing 240 and even 320pounds per reamhave been successfully used.

During the process of manufacturing such paper, alkali and alkali earthsalts of acids from the group ofhyposulfurous, sulfurous, pyrosulfurousand thiosulfuric'acids should be incorporated therein in an amountsuflioient to impart to such paper a content of not less than 1.5% byweight of S0 Larger amounts are preferable, for example, amounts ofbetween 2% and 4%. Sulfite paper or papers made from an incompletelywashed chemical pulp made by the sulfite process (preferably with a highcontent of magnesium sulfite and magnesium thiosulfite) are highlydesirable,'although a sufliciently large content of the correspondingcalcium compounds is also satisfactory. l

Other compounds which'may be incorporated in such sheetmaterialscomprise sodium thiosulfate, the metabisulfites; sodiumpotassium or calcium hyposulfite. Compounds having av relatively lowdissociation constant are preferred since with such compounds the degreeof ionization increases with dilution.

This sheet material may be applied so as to cover the upturned butts ofa layer of lettuce and such sheet either sprinkled with water afterplacement upon the butts or such sheet may be dipped or moistened withwater prior to placement thereof upon the butts. As previously stated.the moistening step may in some instances be eliminated provided,however, a layer of crushed ice is placed over the sheet, water from themelting ice being absorbed by the sheet during shipment. The moisturewhich ordinarily exudes from the butts, as well as the moisture derivedfrom the sprinkling or dipping operations or from the ice, dissolves thechemicals included in the paper and reaction takes place between suchdissolved chemicals and the exudations from the liutts, wherebydarkening is inhibited or reduced for a prolonged period of time. It maybe that the carbonic acid content of the exuded juices reacts with thechemicals somewhat as follows:

In some instances, particularly where the paper contains a relativelyhigh content of sulfltes, the water used in moistening the sheets maycontain a slight quantity-of acid, either mineral or organic, for thepurpose of facilitating the release of S02 therefrom.

The relatively heavy paper to which specific reference has been made notonly'assures the presence of a sufiiciently large quantity of thedesired chemicals, but in addition acts as a bufier in spacing thecrushed ice from the lettuce, thereby preventing the lettuce from beinginjured by the sharp edges and pieces of ice.

It will be found that lettuce packed in the manner described can beshipped to distant markets and be received there in a greatly improvedcondition in comparison with lettuce shipped without such treatment.

This application is a continuation-in-part of the previously mentionedco-pending application Serial No. 322,209.

I claim:

1. As an article of commerce for use in packing leafy vegetables, afibrous sheet containing a sulpho compound, said compound being presentin an amount sufiicient to impart a content of not less than 1.5% $02 byweight to said sheet.

2. As an article of commerce for use in packing leafy vegetables, afibrous sheet weighing not less than 140 pounds per ream, containing asulpho compound, said compound being present in an amount sufficient toimpart a content of not less than 1.5% S02 by weight to said sheet.

3. As an article of commerce for use in packing leafy vegetables, afibrous sheet containing a sulpho compound from the group of alkali andalkali earth salts of hyposulfurous, sulfurous, pyrosulfurous andthiosulfuric acids, said compound being present in amount sufficient toimpart a content of not less than 1.5% S02 by weight to said sheet.

4. As an article of manufacture, absorbent paper having incorporatedtherein a sulpho compound from the group of alkali and alkali earthsalts of hyposulfurous, sulfurous, pyrosulfurous and thiosulfuric acids,said paper containing said sulpho compound in amounts sufiicient toimpart a content of not less than 1.5% S02 by weight.

WILLIAM H. WILSON.

